12,2

J. Goldman and G.-C. Rota, The number of subspaces of a vector space, pp. 75-83 of W. T. Tutte, editor, Recent Progress in Combinatorics. Academic Press, NY, 1969.

I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p, 99.

M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.

Adjacent sequences: A015435 A015436 A015437 this_sequence A015439 A015440 A015441

Sequence in context: A064589 A086644 A011527 this_sequence A082249 A125735 A017544

nonn,easy

Olivier Gerard (olivier.gerard(AT)gmail.com)